In this example it looks as if the array is single quotes then argument value must be in single quotes, and if the array is in double quotes the argument value is double quotes. So, as my testing shows if I were to write this as:

>> ["recycler\n"].include?('recycler\n')

The response is false. As a note I wrote this using OSX 10.7.3 is it may have to do with ruby versions??

So, in writing code do I use single quotes for argument values or double quotes?